WASHINGTON — Boomer politicians are always eager to show off their rock ‘n’ roll bona fides — their iPods filled with Rolling Stones, their Springsteen ticket stubs. But the Maine delegation has coalesced behind a mellower sound: Don McLean.

At a screening of a new documentary about him Tuesday, Sen. Susan Collins, a Republican, explained how her singer-songwriter constituent (he lives in Camden) provided the soundtrack to her recent wedding.

“At our rehearsal dinner, my sister, who is a great musician, asked me what music we wanted. And I said, of course, we have to do ‘American Pie’… I was amazed! My nieces and nephews all knew the words. Talk about having a lasting impact and becoming a part of American culture.”

Another fan from the Pine Tree State was also at the screening organized by the Motion Picture Association of America: former senator and defense secretary Bill Cohen, who played moderator and tried, as have many before him, to get the balladeer to explain his cryptic 8½ minute epic. “American Pie,” McLean said, came from his desire to craft a “big song” that would encompass all the tumult of the 1960s. It ended up, of course, being the massive, generation-crossing singalong smash hit that virtually eclipsed the rest of an otherwise solid career.

Record exec “Clive Davis wanted to give me all these hit songs, but I didn’t believe in them,” McLean said. “I didn’t regret not prostituting myself, though now and again, I guess I did.”

Really? The documentary, “Don McLean: American Troubadour,” which has aired on PBS, depicts a fairly comfortable lifestyle. And legend has it a reporter once asked him what “American Pie” means, and he responded: “That I never have to work again.” True?

“Yes, it’s true,” he laughed. After some unpleasant legal battles in the ’80s, “I own all the songs, all the records.”

Amazing thing about Don McLean: The documentary reveals that his singing voice (“it could cut through steel,” says Brian Wilson) is as clean and pure at 67 as it was at 26.

Healthy living? Not really, McLean said. He drinks; he used to smoke. So how does he do it? “Bed rest,” he told us. “And no yelling.”